Genome and Hormones: Gender Differences in Physiology: Selected Contribution: Gender differences in the endothelin-B receptor contribution to basal cutaneous vascular tone in humans

To testwhether the contribution of endothelin-B (ET-B) receptors to restingvascular tone differs between genders, we administered the ET-Breceptor antagonist BQ-788 into the forearm skin of 11 male and 11 female subjects by intradermal microdialysis. Skin blood flow wasmeasured using laser-Doppler flowmetry at the microdialysis site. Theprobe was perfused with Ringer solution alone, followed by BQ-788 (150 nM) and finally sodium nitroprusside (28 mM) to effect maximalcutaneous vasodilation. Cutaneous vascular conductance (CVC) wascalculated (laser-Doppler flowmetry/mean arterial pressure) andnormalized to maximal levels (%max). In male subjects, baseline CVCwas (mean ± SE) 19 ± 3%max and increased to 26 ± 5%max with BQ-788 (P < 0.05 vs. baseline). In femalesubjects, baseline CVC was 13 ± 1%max and decreased to 10 ± 1%max in response to BQ-788. CVC responses to BQ-788 differed withgender (P < 0.05); thus the contribution of ET-Breceptors to resting cutaneous vascular tone differs between men andwomen. In men, ET-B receptors mediate tonic vasoconstriction, whereas,in women, ET-B receptors mediate tonic vasodilation.